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Flexible and lightweight lithium-ion batteries based on cellulose nanofibrils and carbon fibers.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.ORCID iD: 0000-0003-1713-1659
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.ORCID iD: 0000-0002-2029-4945
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.ORCID iD: 0000-0001-9203-9313
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.ORCID iD: 0000-0001-5816-2924
(English)In: Journal of Power SourcesArticle in journal (Other academic) Submitted
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-205656OAI: oai:DiVA.org:kth-205656DiVA, id: diva2:1089912
Note

QC 20170421

Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2018-05-07Bibliographically approved
In thesis
1. Wood-based Materials for Lithium-ion Batteries
Open this publication in new window or tab >>Wood-based Materials for Lithium-ion Batteries
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lithium-ion batteries (LIB) have become very important recently as power sources for portable electronics and electric vehicles. Today non-renewable petroleum-based polymers are used as binders in state-of-the-art LIB. Therefore, it is essential to investigate alternative binders, which are environmentally friendly and inexpensive. Using wood-based materials, such as cellulose and lignin, could make the batteries more environmentally benign, cheaper and easier to produce.

Lignin, a byproduct from the pulping industry and the second most abundant bio-polymer in wood, has been investigated for the first time as binder material for eco-friendly LIB. Both LiFePO4 (LFP) positive and graphite negative electrodes using pretreated lignin as binder exhibited good electrochemical performance. The drawback of lignin as binder is that its poor mechanical properties limit the preparation of a thick electrode, constraining the energy density for LIB.

In order to meet the demands of flexible and bendable electronic devices, cellulose nanofibrils (CNF) as binder materials have been successfully fabricated for flexible batteries by a water-based paper making process. It showed excellent binding properties for different kinds of electrode materials, which were homogenously dispersed in its visible network. The flexible electrodes obtained good mechanical and electrochemical properties. A study of different CNF shows that the manufacturing process affects the performance of the electrodes.

Another innovative LIB concept in this thesis was to build both lightweight and bendable LIB. Chopped carbon fibers (CF), bound by CNF, were demonstrated as both current collector and as a current collector-free negative electrode, produced by an easy filtration process. The gravimetric energy density was increased compared to cells with metallic current collectors. The CF-based lightweight and flexible electrode achieved a good cycling stability, rate capability, even after 4000 times of bending.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2017. p. 48
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2017:26
Keywords
binder, lignin, TEMPO-oxidized cellulose nanofibrils, flexible paper electrodes, lightweight, eco-friendly, Li-ion batteries
National Category
Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-205663 (URN)978-91-7729-358-3 (ISBN)
Public defence
2017-05-22, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20170421

Available from: 2017-04-21 Created: 2017-04-21 Last updated: 2017-04-24Bibliographically approved
2. Carbon Fibres for Multifunctional Lithium-Ion Batteries
Open this publication in new window or tab >>Carbon Fibres for Multifunctional Lithium-Ion Batteries
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The transportation industry today faces many challenges because of the rapid movement towards electrification. One major challenge is the weight of the battery, which limits the effectiveness of the vehicles. One of the possible routes to reduce the weight on a system-level is introducing structural batteries, batteries that simultaneously storeenergy and hold a mechanical load. Placing these batteries in a load-bearing part of the structure reduces weight and increases effectiveness on a system level. Carbon fibres are especially suited for structural batteries because of the high performance as reinforcement material in a polymer composite, as well as the ability to insert lithium to function as negative electrodes in batteries.

Another field that has attracted attention the latest years is flexible batteries due to the emerging of flexible displays and wearable electronics. Carbon fibres can be a suitable material in flexible batteries due to the good conductivity, mechanical integrity and ability to forman integrated flexible film with cellulose nanofibrils (CNF) as binder.

This thesis focuses on the usage of carbon fibres in structural and flexible batteries. Lignin based and commercial carbon fibres are evaluated as negative electrodes using a combination of electrochemical methods, material characterization and mechanical testing. Further, the diffusion is characterized using nuclear magnetic resonance spectroscopy, revealing an inequality of axial and radial diffusion in carbon fibres. The carbon fibres with a largely disordered structure show most promise as a negative electrode, with a capacity similar to graphite and having a high coulombic efficiency.

Carbon fibres used as current collectors are evaluated as well, both continuous LiFePO4 coated carbon fibres with electrophoretic deposition for structural positive electrode applications and chopped carbonfibres bounded by CNF as a layer in a flexible electrode. The LiFePO4 coated carbon fibres show promise as a structural electrode with moderatecapacity, high coulombic efficiency, good rate performance and good adhesion between fibres and coating. The flexible electrodes with carbon fibres as current collectors perform well with a high capacity, good rate performance, low weight and high flexibility. The electrodes withstand bending for 4000 times without any performance degradation.

Place, publisher, year, edition, pages
Kungliga tekniska högskolan, 2018. p. 78
National Category
Other Chemical Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-227296 (URN)978-91-7729-763-5 (ISBN)
Public defence
2018-05-30, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Energy Agency, 37712-1
Note

QC 20180507

Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-05-07Bibliographically approved

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Lu, HuiranHagberg, JohanLindbergh, GöranCornell, Ann M.

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